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    This motion detector alarm can detect a moving person from a distance of 1 meter. It uses a dual IR Transmitter-Receiver module HOA1405. When the sensor detects the reflected IR rays, alarm will sound for 2 minutes. The circuit can be modified for various applications including AC operated alarm systems.

    Schematic of the Motion Detector Circuit

    motion detector alarm circuit

    IR Dual Reflective Sensors

    The main element in the movement detector circuit is the dual IR reflective sensor HOA1405. It has a built in IR diode and an NPN Photo transistor. The black covering of the module filters visible light rays and allow IR rays to fall on the Photo transistor.

    When the Photo transistor receives IR rays, it conducts. The collector of the Photo transistor is connected to the trigger pin2 of a short duration Monostable timer built around IC NE 555.

    With the given values of R4 and C2, output of IC1 remains high for two minutes to light LED and to activate the buzzer. In the standby state, the photo transistor inside the Dual Reflector module remains non conducting since its base is not getting IR rays.

    When a person comes in front of the module, the reflected IR rays will trigger the Photo transistor and its Collector goes to ground potential.
    This triggers the Monostable and Alarm sounds.

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
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    45 Responses to "Motion Detector Alarm Circuit"

    1. anil kumar lines says: on March 25, 2010 at 7:55 am

      is this movement detecor is using for automatic door opener when a person comes in front of a door

      • thank you for your project its really working fabulously im a beginner bt i made a small change in the circuit and i added lm358 ir sensor circuit at with this 555 timer circuit and also slight changes in the lm358 circuit , i kept the light not beside instead i kept face to face ,,,

      • thank you for your project its really working fabulously im a beginner bt i made a small change in the circuit and i added lm358 ir sensor circuit at with this 555 timer pin 2 instead of the dual reflector and also slight changes in the lm358 circuit , i kept the light not beside instead i kept face to face ,,,

    2. This circuit can be used for automatic door opener with suitable relay operated mechanical arrangements

      • bro is this circuit working??? can u confirm it???

      • manjunath madabavi says: on March 20, 2014 at 5:19 pm

        i am not perfect in inglish so please adjest it
        i am B.com student from bagalakot Dst,
        I am poor i want study with deploma or B.E or other engineering clg, but u know i have no more money.so,please help me any one
        i want learn about electronics so please
        guid me or which book i read please sir email me book name or other way of learning about electranics
        my email account

      • Electronics Eng. by J.S. Katre -Tech Max publication is a nice book for basics of Electronics. You may also prefer Electronics For You monthly magazine for recent technologies & some small projects.

    3. can i replace the speaker with lamp 12V

    4. i already assemble the circuit properly,why its not working??any advice??

    5. can we have the calculations of the values on the circuit to see how did the values of components found? may be we can be able to troubleshoot the fault when the circuit is not working.

    6. the working principles of the stages of the motion detector

    7. i already try the circuit but the alarm keep on ringing when i havent passthrough the sensor yet but when the alarm stop n i try to pass through the sensor nothing happen? Any suggestion what wrong with it?

    8. i already did the circuit but when i havent pass through the sensor yet the alarm already ringing for a long time but when it stop ring and i try to pass through the sensor nothing happen. Any idea what happen?
      plz reply asap coz my project date almost near….

    9. sir i want to know about the cost of dual ir reflector

    10. How do i modify this circuit into one that can transmit a signal unto a receiver when the alarm blows?

    11. Please inform detecting distance.Thanks.

      • Were you tired?.First Line.This motion detector alarm circuit can detect a moving person from a distance of 1 meter.

    12. Can you give me another alternative device for HOA1405

    13. theres no reply why isnt it working ?

    14. thx to give us that circuit but no value of speacker.can u give me the value of the speacker? and i see that,that crct works in the reverse.

    15. is this circuit can be use as monostable vibrator for counter?

    16. Hello Everyone,

      Where Can I buy all stuff ? If I use this Schematics circuit will I make it ?

      Any advice.

      Thank you. Have a good day

    17. sir anyone plz tel me is this ciruit working or nt??? im going to implement it plz hury up

    18. will this circuit work? n where can i buy all the devices required? can anyone tell me please..

    19. Hello Jeff,

      May I have your website address ?

      Thank you


    20. Hi Nani,

      You can get them from Conrad electronics. if you are in western Europe.

      Have a good day.


    21. Hello,

      I have made a Solar mobile charger from my 18V solar cell, 5V(LM7805) Voltage regulator and USB. It used to work for my Samsung Mobile 3.70Wh but now it is not working any more. With other samsung mobile which has a battery 2.7V it is still working. where is the problem ? I am eager to know. Thank you for your help in advance


    22. salam,,,,still no comment about is this circuit working or nt ,,,anyone there who implement it?????????

    23. Is R3 470 ohms??? and C1 is 0.01 micro F or just 0.01 F??? please reply me as soon as possible…please…thank you….

      • Jim Keith says: on October 9, 2012 at 3:49 pm

        Yes, 470 is in ohms and 0.01 is in uF.

        Looking at the circuit and reading the comments, I believe that R2 should be much higher to get any kind of range. I recommend a 10K or 100K pot so the threshold may be easily varied.

    24. can this circuit be added with a dc motor…so that when the sensor triggers, it activates a motor???

      • Jim Keith says: on October 9, 2012 at 5:31 pm

        Yes, it may be modified so that it can drive a motor, but first get it working as is before going this far. Also check out my other comment on range.

    25. The article states up to 1M, but the spec sheet indicates peak response at 5mm. I have experimented with these sensors and know from experience that even 100mm is wishful thinking.

      The HOA1405 assembly is pre-focused and angled for optimum 5mm sensitivity. Better range may be obtained via using discrete emitter and photo-transistor (narrow angle) components so that they may be focused at a more distant surface. The nature of the surface is also an issue in order to reflect back a reasonable amount of light. Also, a visible light filter is necessary so that ambient light does not interfere with the photo-transistor. Some photo-transistors have integral filters.

    26. so your saying the maximum sensitivity of this sensor is 5mm?? any ways to solve this???

    27. stupid ass circuit….its a bullshit….can detect the length of 1 meter my ass….

    28. can i use a pir motion sensor instead of the dual reflective sensor using the same diagram above

    29. what software that have the component of HOA1405?can you reply it as soon as possible..

    30. Does NOR LATCH CIRCUIT work with this system or the NAND LATCH CIRCUIT.

    31. all fine

    32. Can i implement a electronic map for any organization or a college campus by using it’s data base of that organization?????
      Plzzz give me some suggations….idea to implement it…..

    33. Yes it works!!

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